function watermark(setting) {
  var key;
  // 默认设置
  var defaultSettings = {
    watermark_id: '',
    watermark_txt: 'text',
    watermark_x: 20, // 水印起始位置x轴坐标
    watermark_y: 20, // 水印起始位置Y轴坐标
    watermark_rows: 20, // 水印行数
    watermark_cols: 20, // 水印列数
    watermark_x_space: 100, // 水印x轴间隔
    watermark_y_space: 50, // 水印y轴间隔
    watermark_color: '#aaa', // 水印字体颜色
    watermark_alpha: 0.3, // 水印透明度
    watermark_fontsize: '14px', // 水印字体大小
    watermark_font: '微软雅黑', // 水印字体
    watermark_width: 210, // 水印宽度
    watermark_height: 80, // 水印长度
    watermark_angle: 15, // 水印倾斜度数
    watermark_position: 'fixed',
  };
  // 采用配置项替换默认值，作用类似jquery.extend
  if (arguments.length === 1 && typeof arguments[0] === 'object') {
    var src = arguments[0] || {};
    for (key in src) {
      if (src[key] && defaultSettings[key] && src[key] === defaultSettings[key]) {
        continue;
      } else if (src[key]) {
        defaultSettings[key] = src[key];
      }
    }
  }

  var oTemp = document.createDocumentFragment();

  // 获取页面最大宽度
  var page_width = 0;
  if (document.getElementById(defaultSettings.watermark_id)) {
    page_width = Math.max(document.getElementById(defaultSettings.watermark_id).scrollWidth, document.getElementById(defaultSettings.watermark_id).clientWidth);
  }
  var cutWidth = page_width * 0.015;
  var page_width = page_width - cutWidth;
  // 获取页面最大高度
  var page_height = 0;
  if (document.getElementById(defaultSettings.watermark_id)) {
    page_height = Math.max(document.getElementById(defaultSettings.watermark_id).scrollHeight, document.getElementById(defaultSettings.watermark_id).clientHeight) + 450;
  }
  // var page_height = document.body.scrollHeight+document.body.scrollTop;
  // 如果将水印列数设置为0，或水印列数设置过大，超过页面最大宽度，则重新计算水印列数和水印x轴间隔
  if (defaultSettings.watermark_cols == 0 || parseInt(defaultSettings.watermark_x + defaultSettings.watermark_width * defaultSettings.watermark_cols + defaultSettings.watermark_x_space * (defaultSettings.watermark_cols - 1)) > page_width) {
    defaultSettings.watermark_cols = parseInt((page_width - defaultSettings.watermark_x + defaultSettings.watermark_x_space) / (defaultSettings.watermark_width + defaultSettings.watermark_x_space));
    defaultSettings.watermark_x_space = parseInt((page_width - defaultSettings.watermark_x - defaultSettings.watermark_width * defaultSettings.watermark_cols) / (defaultSettings.watermark_cols - 1));
  }
  // 如果将水印行数设置为0，或水印行数设置过大，超过页面最大长度，则重新计算水印行数和水印y轴间隔
  if (defaultSettings.watermark_rows == 0 || parseInt(defaultSettings.watermark_y + defaultSettings.watermark_height * defaultSettings.watermark_rows + defaultSettings.watermark_y_space * (defaultSettings.watermark_rows - 1)) > page_height) {
    defaultSettings.watermark_rows = parseInt((defaultSettings.watermark_y_space + page_height - defaultSettings.watermark_y) / (defaultSettings.watermark_height + defaultSettings.watermark_y_space));
    defaultSettings.watermark_y_space = parseInt((page_height - defaultSettings.watermark_y - defaultSettings.watermark_height * defaultSettings.watermark_rows) / (defaultSettings.watermark_rows - 1));
  }
  var x;
  var y;
  for (var i = 0; i < defaultSettings.watermark_rows; i++) {
    y = defaultSettings.watermark_y + (defaultSettings.watermark_y_space + defaultSettings.watermark_height) * i;
    for (var j = 0; j < defaultSettings.watermark_cols; j++) {
      x = defaultSettings.watermark_x + (defaultSettings.watermark_width + defaultSettings.watermark_x_space) * j;

      var mask_div = document.createElement('div');
      mask_div.id = 'mask_div' + i + j;
      mask_div.className = 'mask_div';
      mask_div.appendChild(document.createTextNode(defaultSettings.watermark_txt));
      // 设置水印div倾斜显示
      mask_div.style.webkitTransform = 'rotate(-' + defaultSettings.watermark_angle + 'deg)';
      mask_div.style.MozTransform = 'rotate(-' + defaultSettings.watermark_angle + 'deg)';
      mask_div.style.msTransform = 'rotate(-' + defaultSettings.watermark_angle + 'deg)';
      mask_div.style.OTransform = 'rotate(-' + defaultSettings.watermark_angle + 'deg)';
      mask_div.style.transform = 'rotate(-' + defaultSettings.watermark_angle + 'deg)';
      mask_div.style.visibility = '';
      mask_div.style.position = defaultSettings.watermark_position;
      mask_div.style.left = x + 'px';
      mask_div.style.top = y + 'px';
      mask_div.style.overflow = 'hidden';
      mask_div.style.zIndex = '999';
      mask_div.style.pointerEvents = 'none'; // pointer-events:none  让水印不遮挡页面的点击事件
      // mask_div.style.border="solid #eee 1px";
      mask_div.style.opacity = defaultSettings.watermark_alpha;
      mask_div.style.fontSize = defaultSettings.watermark_fontsize;
      mask_div.style.fontFamily = defaultSettings.watermark_font;
      mask_div.style.color = defaultSettings.watermark_color;
      mask_div.style.textAlign = 'center';
      mask_div.style.width = defaultSettings.watermark_width + 'px';
      mask_div.style.height = defaultSettings.watermark_height + 'px';
      mask_div.style.display = 'block';
      oTemp.appendChild(mask_div);
    }
  }
  if (document.getElementById(defaultSettings.watermark_id)) {
    document.getElementById(defaultSettings.watermark_id).appendChild(oTemp);
  }
}
export default watermark;
